Vehicular remote power supply system

ABSTRACT

A vehicular remote power supply including a main relay connected to the field terminal of the vehicle generator which relay operates, in response to connection of a remote load to the power supply, to disconnect the generator field terminal from the vehicle regulator and to connect the generator field terminal with the vehicle battery. The relay also operates to cause energization of a solenoid which, in turn, moves a plunger to advance the engine throttle thereby increasing engine speed. When the throttle has advanced a predetermined distance, it operates a protective switch which disconnects the generator from the battery. The remote load can be a hand tool or similar appliance, a storage battery to be charged, or a welding electrode, in which latter case the system includes timing means and renders the generator self-excited.

O United States Patent [151 3,681,611 Watson 1 Aug. 1, 1972 [54]VEHICULAR REMOTE POWER Primary Examiner-Robert K. Schaefer SUPPLY SYSTEMAssistant Examiner-William J. Smith 72 Inventor: M A. Watson, Boise,Idaho [73] Assignee: Soltronlmlnc, Boise, Idaho [57] ABSTRACT [22]Filed: May 26,1971 A vehicular remote power supply including a mainrelay connected to the field terminal of the vehicle [211 App! generatorwhich relay operates, in response to connec n w [1,5, Appllcgfim D ttion of a remote load to the power supply, to disconf S N 91 316 N nectthe generator field terminal from the vehicle [63] conunuauon'ln'pan 4regulator and to connect the generator field terminal with the vehiclebattery. The relay also operates to cause energization of a solenoidwhich, in turn, moves "307/ a ph g advance th engine tin-on]: therebyina l I a v a a s a u a I a I a Q a c 0 o a e a o a u a o n u w e w a na a n o a a a. l I [58] new a smch "mun/lo 10 2435 vanced apredetermined distance. it operates a protective switch whichdisconnects the generator from the a battery. The remote load can be ahand tool or similar [56] Rem-em CM appliance, a storage battery to becharged, or a weld- UMTED STATES PATENTS ingelectrode, in which lattercase the system includes 3 293 443 [2/1966 urc 307/10 R timing means andrenders the generator self-excited.

14 Claims, 1 Drawing Figure Reguotor 4 Rectifier l6 N Means 5 VehicleAilernator 8 8 Load Ci CUlTS Welding Electrode 1 56 i l L 87. l 69-* r 3J I T l "I i 40 ,|4 32 I 22 2 I I I'" Plunger I Q l 1 1 R" k eevea I T30L J 2e 2e VEHICULAR REMOTE POWER SUPPLY SYSTEM CROSS REFERENCE TO ARELATED APPLICATION This invention is a continuation-in-part of mycopending application, Ser. No. 9l,3l6, now U.S. Pat. No. 3,614,459filed Nov. 20, I970 and entitled Vehicular Remote Power Supply System".

BACKGROUND OF THE INVENTION The present invention relates to a powersupply for operating a remote load from the electrical system of avehicle and, more particularly, to a new and improved vehicular remotepower supply which automatically provides isolation and overloadprotection for the vehicle electrical system.

Various types of remote or emergency power supply systems operable fromthe conventional electrical system of an automotive vehicle have beenproposed in the patented prior art. In the patents to Burch U.S. Pat.No. 3,293,443, Schneider U.S. Pat. Nos. 3,456,l l9 and 3,471,706 andChilton et al. No. 3,497,709, various types of vehicular power supplysystems are disclosed for operating power hand tools or accessories, forcharging storage batteries, or for converting, inverting or varying themagnitude of the voltage produced by the dynamo of the vehicle. As shownin the patents to Brown U.S. Pat. No. l,528,364, McEniry U.S. Pat. No.2,182,030 and Anderson U.S. Pat. No. 2,976,424, it has been proposed tosupply electrical power from the vehicle electrical system to weldingelectrode means, use being made of solenoid means to advance thethrottle to increase the engine speed and thereby drive the dynamo at ahigher generating speed.

In general, the known auxiliary vehicle power supply systems requireclosure of a manual switch to initiate system operation. This switchusually is operable to break the electrical connection between theoutput post of the dynamo and the vehicle battery, thereby permittingthe dynamo output voltage to be elevated to the desired voltage byappropriate regulation of the speed of the dynamo. One hazard presentedby such a system is that excessive current can flow and cause damage tothe dynamo and associated components such as rectifier diodes in theevent that the switch is left in the operating position without anelectrical load being placed across the dynamo.

Another disadvantage of several of the prior semi-automatic vehicularpower supply systems is that some type of vacuum-operable means arecommonly used to advance the throttle. These types of systems areexpensive to install, and a small leak in the vacuum line will renderthem totally inoperable. A further drawback of the known system is therequirement for provision of a fuse in one side of the high voltagecircuit to prevent overloading of the dynamo, thereby eliminating thedynamo from use as a source of power for a maximum amperage welder orbattery charger.

SUMMARY OF THE INVENTION put voltage and which automatically providesisolation and overload protection for the vehicle electrical system.Furthermore, the system desirably will be placed in operation only inresponse to connection of the remote load. It also would be desirable toprovide such a system for uses a manually operable battery charger whichgives an alarm when the battery-chug ing cables are connected with thewrong polarity. In addition, it would be advantageous to provide withsuch a system an automatic welding apparatus including timedelayedoperation and self-excitation of the vehicle generator.

The present invention provides a vehicular remote power supply systemwhich operates, in response to connection of a remote load thereto, toisolate the vehicle regulator from the field terminal of the vehiclegenerator and to apply a suitable excitation voltage to the generatorfield terminal. The system then operates to increase the speed of thevehicle engine and, therefore, to drive the generator at an increasedspeed to provide a high d.c. output voltage. When the engine speed hasbeen increased by a predetermined amount, the generator armatureterminal is isolated from the vehicle d.c. voltage source or battery.The remote load can comprise a battery to be charged, in which case thesystem provides an alarm signal when the battery cables are connectedimproperly. When the remote load comprises welding electrode means, thepower supply system begins operation a predetermined time afterengagement between the welding electrode and a workpiece. In addition,the generator field terminal is disconnected from the regulator fieldterminal and connected to'the generator armature terminal whereby thegenerator is electrically self-excited.

While a single specific embodiment of the principles of the presentinvention is illustrated in the, accompanying drawing and described indetail in the following specification, it is to be understood that suchembodiment is by way of example only and that various mechanicalmodifications may be made without departing from the spirit of theinvention, the scope of which is limited only as defined in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWING FIGURE The single FIGURE of the drawingis a schematic diagram of a vehicular remote power supply systemaccording to the present invention.

DETAILED DESCRIPTION 0E THE PREFERRED EMBODIMENT Referring now to thedrawing, the conventional vehicle d.c. voltage source or battery 2 isconnected with the battery terminal B of the regulator 4 via theignition switch 6. The regulator includes also armature and neutralterminals A and N that are directly connected with the correspondingterminals'of the conventional vehicle generator in the form ofalternator 8, and a field terminal F that is normally connected with thealternator field terminal via conductor 10, a two-position first fieldswitch 12, and conductor 14. The armature terminal of the alternatorsupplies power to the vehicle load circuits 16 via rectifier means 18arranged either within or separate from the alternator. The alternator 8is driven by the internal combustion engine 20, the speed of operationof which is controlled by the throttle means 22. For purposes ofconvenience, the term generator is used herein to refer to both thecommonly known d.c. type generator and the ac. type generator, thelatter being commonly referred to as an alternator. In the vehicleelectrical system of the present illustration, alternator 8 is assumedto include built-in rectifier means for convenience in describing thepower supply circuit of the present invention.

in accordance with the present invention, means responsive to a demandfor high voltage power are antomatically operable to short out theregulator field control of the alternator and to increase the operatingspeed of the engine, thereby to drive the alternator at a highergenerating speed. More particularly, there is provided electromechanicalmeans compr'ning solenoid means 26 including a pull-in coil 28, ahold-in coil 30 and a solenoid plunger 32 for operating the throttlecontrol 22 to increase the engine drive speed. Plunger 32 is suitablymechanically connected to throttle means.

22. Power is supplied to one end of the solenoid pull-in ground switch38. The alternator armature terminal A 25 is connected with the d-cvoltage source via conductor 37 and armature switch 39, which comprisesanother pole of the protective switching means. The protective switchingmeans is suitably mechanically connected to plunger 32 whereby switches36 and 39 are opened when throttle 22 has been moved by plunger 32through a predetermined distance. V

The apparatus of the present invention further comprises electricallyoperated switching means, selectively connected by energizing means tod.c. voltage source 35 .2, operable when energized to disconnect thefield terminal of alternator 8 from the field terminal of regulator 4and to connect the alternator field terminal to d.c. source 2. Inparticular, the first field switch 12 and the ground switch 38 areoperable by a normally de-energized main relay 46 that is connected withthe d-c voltage source 2 via a normally open Reed switch 48. Switch 48is operable by a current responsive means in the form of actuating coil50 that is connected at one end with the armature terminal of alternator8 via fuse 52. The other end of actuating coil is connected withelectrical ground when a remote load designated 69 is connected tooutlet receptacle 54. voltmeter means 56 are provided for reading thehigh direct-cur- 50 rent output voltage appearing at the receptacle 54.By virtue of this arrangement, the electrically operated switching meansis energized only when a load of sufficient magnitude is connected toreceptacle 54, thereby protecting against the hazard of excessivecurrent flow.

The apparatus of the present invention also can supply a relatively highd.c. voltage for charging a storage battery. To this end, the armatureterminal of alternator 8 is connected through a normally open,

isolation or battery charging switch 60 to one terminal 60 of a batterycharging outlet receptacle 62, the other terminal of which is connectedto electrical ground. Switch 60 is closed in response to energization ofa coil 64 which, in turn, is connected through a manually operatedd.p.d.t switch 66 to d.c. voltage source 2. An

alarm 67 and forward current diode 68 are connected across outletreceptacle 62 to provide an audible alarm if the battery cablesareconnected with the wrong polarity.

When switch 60 is closed, the battery properly connected to receptacle62 is connected to the positive side of the charging alternator 8, andthe number of battery cells being charged determines thechargingvoltage. Switch 60 is closed, however, only in response to manualoperation of switch 66 because of the potential dangers associated withbattery charging, such as I ignitable gas which can be present around abattery and damage resulting from wrong polarity connections.

The apparatus otthe present invention described thus far operates in thefollowing manner. With the vehicle engine idling, when a remote load 69of predetermined magnitude, such as a minimum of 100 watts, is pluggedinto receptacle 54, current flows through coil 50 closing switch 48 andenergin'ng relay 46 from d.c. voltage source 2. Load 69 can be a handtool or similar appliance requiring adc. voltage of about 0 volts.Alternatively a battery to be charged is connected through cables toreceptacle 62' and switch 66 is placed in the battery charging positionas shown in the drawing. Relay 46 is energized from d.c. source 2 alongwith coil 64 which, in turn, closes switch 60 to connect the armatureterminal of alternator 8 to the battery to be charged.

In either case the electrically operated switching means comprisingrelay 46 is energized from d.c. voltage source 2 in response toconnection of a remote load. When main relay 46 is energized, it closesground switch 38 to energize solenoid pull-in coil 28, and first fieldswitch 12 is operated to the second position to isolate the regulatorfield terminal and to connect the alternator field terminal directlywith the d-c cource 2 via conductor 14, switch 12, and conductors 70 and34. Owing to the energization of pull-in coil 28, solenoid plunger 32 isdisplaced from its de-energized position toward its fully energizedposition, thereby advancing the throttle 22 to increase engine drivingspeed and, consequently, to increase the speed at which the alternator 8is driven. When the solenoid plunger reaches the fully energizedposition, pull-in switch 36 and armature switch 39 are opened by theplunger, thereby deenergizing the pull-in coil 26 and isolating thealternator armature terminal from the d-c voltage source. The solenoidplunger is now maintained in the fully energized position by the hold-incoil 30 that is energized by d.c. voltage source 2 through conductor 34and switch 38. Alternator 8 therefore is driven at a relatively highspeed to supply a relatively high rectified d.c. voltage to a loadconnected to receptacle 54 or to a storage battery connected toreceptacle 62 for charging the battery. The armature terminal ofalternator 8 is isolated from the d.c. source 2 automatically when thehigh speed operation is attained.

in accordance with another significant feature of the invention, awelding electrode is provided for engagement with a workpiece 82, thewelding electrode being connected with the armature terminal ofalternator 8 through a timing coil 84 and a conductor 88. At the start,switch 66 is moved to the other position, opposite that shown in thedrawing, which corresponds to welding. When welding electrode 80 isbrought into engagement with the workpiece 82, timing coil 84 isenergized to effect closure of the normally open timing switch 86,whereupon the control electrode of the normally nononductive transistor90 is connected with the d-c voltage source 2 through a bleeder resistor92, an r-c timing circuit 94, switch 86 and a conductor 96. Whentransistor 90 conducts, welder relay 98 is energized from d.c. voltagesource 2 through switch 66 and a conductor 99. This, in turn, operatesthe welder switch 100 to connect the main relay 46 with the do source 2,and operates the two-position second field switch 102 to isolate theregulator field terminal by disconnecting it from the alternator fieldterminal and to connect the alternator field terminal with thealternator armature terminal by means of conductor 14, switch 102, andconductor 37. Alternator 8 now is connected in an electricallyself-excited condition. Energization of relay 46 operates switch 46 asin the foregoing operation to disconnect the field terminal ofalternator 8 from the field terminal of regulator 4 and to convert thealternator field terminal with d.c. source 2. Energization of relay 46also closes ground switch 38 to energize solenoid means 26 and moveplunger 32 to operate engine 20 at a high driving speed, whereuponalternator 8 is driven to supply the high welding voltage to the weldingelectrode means. When plunger 32 reaches the fully energized position,the armature switch 39 is opened to isolate the alternator armatureterminal from the d-c voltage source 2, and the switch 36 is opened tode-energize the pull-in coil 28. The position of plunger 32 ismaintained by coil 30.

When the welding process is initiated, the striking voltage is loweredto about 20 volts by the load placed on it, thereby raising the currentflow through the selfexcited alternator 8. The delay system is providedsince a prolonged voltage of more than 30 volts would be harmful to thefield of alternator 8, and further to assist in the striking of thewelding are. The welding relay 98 stays closed until the capacitor inthe delay network 94 is discharged, the time normally being about 3seconds as determined by bleeder resistor.

Preferably the solenoid plunger 32 is connected with throttle 22 bymeans of a motorcycle-type cable with screw adjustments at both ends,whereby the speed of alternator 8 may be regulated to make it a low orhigh output charger. in the case of a high d.c. power unit, one therebyhas the ability to set the voltage as desired.

It is important to note that while the high d-c power supply and weldingsystems are fully automatic, the battery charging system isintentionally designed for manual operation, as previously mentioned,because of the danger of an arc igniting the hydrogen that is formedaround a battery, and because of the damage that results from connectinga battery with the wrong polarity.

I claim:

1. A vehicular remote power supply adapted for use with a vehicleelectrical system including a d.c. voltage source; a generator havingarmature and field terminals for producing a d.c. output voltage; aregulator having a field terminal, a battery terminal connected to saidvoltage source, and an armature terminal connected to said generatorarmature terminal; said generator being driven by the internalcombustion engine of the vehicle controlled by throttle means; saidremote power supply comprising:

a. means for connecting said generator armature terminal to a loadhaving a relatively high d.c. voltage requirement;

b. electrically operated switching means normally connecting saidgenerator field terminal to said regulator field terminal and operablewhen electrically energized to disconnect said generator field terminalfrom said regulator field terminal and to connect said generator fieldterminal to said d.c. voltage source;

. energizing means for selectively connecting said d.c. voltage sourceto said switching means for causing operation thereof; and

d. protective switching means operable to disconnect said generatorarmature terminal from said d.c. voltage source after said throttlemeans has been advanced through a predetermined distance.

2. Apparatus according to claim 1 further including electromechanicalmeans mechanically connected to said throttle means and electricallycoupled by said electrically operated switching means to said d.c.voltage source for moving said throttle means to increase engine speedwhen said electro-mechanical means is energized by said d.c. voltagesource.

3. Apparatus according to claim 2 wherein said protective switchingmeans is mechanically coupled to said electromechanical means andnormally connects said generator armature terminal to said d.c. voltagesource and operates to disconnect said generator armature terminal fromsaid d.c. voltage source when said electromechanical means has advancedsaid throttle means through a predetermined distance.

4. Apparatus according to claim 3 wherein said protective switchingmeans also normally connects said d.c. voltage source to saidelectromechanical means and disconnects said d.c. source from saidelectromechanical means also when said throttle means has been movedthrough said predetermined distance, and wherein said electromechanicalmeans includes holding circuit means connected to said d.c. voltagesource by said electrically operated switching means when the latter isoperated.

5. Apparatus according to claim 1 wherein said loadconnecting meansincludes current responsive means and wherein said energizing means isconnected in controlled relation to said current responsive meanswhereby said energizing means connects said d.c. voltage source to saidelectrically operated switching means only when a load is connected tosaid generator armature terminal.

6. Apparatus according to claim 1 wherein the load is a battery to becharged having opposite polarity terminals, wherein said energizingmeans includes manually operated switching means for connecting saidd.c. voltage source to said electrically operated switching means, andwherein said load connecting means includes isolation switch meansconnected in controlled relation to said energizing means for connectingsaid battery to be charged to said generator armature terminal when saidelectrically operate switching means is energized.

7. Apparatus according to claim 6 further including alarm meansconnected to said load connecting means for indicating an improperpolarity connection of said battery terminals relative to said generatorarmature terminal.

8. Apparatus according to claim 1 wherein the load comprises weldingelectrode means adapted to be brought into engagement with a workpiece,wherein said load-connecting means includes means responsive toengagement of said welding electrode means with said workpiece, whereinsaid energizing means is connected in controlled relation to saidengagement responsive meanS whereby said electrically operated switchingmeans is operated when said welding electrode means is in engagementwith said workpiece, and wherein said apparatus further comprisesswitching means connected in controlled relation to said energizingmeans and normally connecting said generator field terminal to saidregulator field terminal and operated by said energizing means todisconnect said generator field terminal from said regulator fieldterminal and to connect said generator field terminal to said generatorarmature terminal whereby said generator is electrically self-excited.

9. Apparatus according to claim 8 wherein said energizing means includestime delay means for operating said electrically operated switchingmeans only a predetermined time after engagement between said weldingelectrode means and said workpiece.

10. Apparatus according to claim 1 wherein said electrically operatedswitching means comprises relay means having a control coil connectedbetween said energizing means and electrical ground, a first switchingmeans connecting said generator field terminal to either said regulatorfield terminal or said dc voltage source depending upon the electricalcondition of said coil, and a second switching means electricallyconnecting said electromechanical means to said dc. voltage source whensaid coil is energized.

11. Apparatus according to claim 2 wherein said electro-mechanical meanscomprises solenoid means having a coil connected between said d.c.source and said electrically operated switching means in a manner so asto be energized when said switching means is operated and a plungermechanically connected to said throttle means for moving said throttlemeans in response to energization of said coil.

12. Apparatus according to claim 10 wherein said energizing meansincludes normally open reed switch means for connecting said do sourceto said coil of said electrically operated switching means, said reedswitch means having a control coil connected in series with saidload-connecting means whereby said dc. voltage source is connected tosaid coil of said electrically operated switching means only when a loadis connected to said generator armature terminal.

13. Apparatus according to claim 11 wherein said electromechanical meansfurther includes a holding coil connected to said dc. voltage source bysaid electrically operated switching means when the latter is operatedso as to maintain said plunger in a given position when said solenoidcoil is de-energized, and wherein said protective switching means isoperatively connected to said plunger and also normally connects said dcvoltage source to said solenoid coil and disconnects said coil when saidplunger has moved said throttle means through said predetermineddistance.

14. Apparatus according to claim 1 wherein the load comprises weldingelectrode means adapted to be brought into engagement with a workpieceand "L'Tfififi a ri'ifli'sli'lfiilif 'li'iiii having a first positionwherein said electrically operated switching means is disconnected fromsaid dc voltage source and said generator field terminal is connected tosaid regulator field terminal and operable in response to a flow ofcurrent through said coil to a second position connecting said dc.voltage source to said electrically operated switching means andconnecting said generator field terminal to said generator armatureterminal whereby said generator is electrically self-excited;

. means connecting one terminal of said coil to said dc. voltage source;

c. semiconductor switching means having a control terminal and connectedto the other terminal of said coil in a manner such that when saidsemiconductor means is rendered conducting current flows through saidrelay coil;

. an R-C timing circuit connected to said semiconductor means controlterminal whereby said semiconductor means is switched into a conductingstate a predetermined time delay after a voltage of sufficient magnitudeis applied to said timing circuit; and

e. a second relay means having a coil and operable to connect a voltageof said sufficient magnitude to said timing circuit in response toenergization of said coil, said coil being connected to said loadconnecting means in a manner whereby said coil is energized in responseto engagement of said welding electrode means with said workpiece.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,681,611 Dated August 1, 1972 Inventor(s) Fred A. Watson It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

The assignee named in the heading of the patent should be Inc., Boise,Idaho.

Signed and sealed this 3rd day of April 1973.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.PLETCHER,JR.

Commissioner of Patents Attesting Officer F 0PM PC1-1050 {10-691 n u z,GOVERNMENT PFHNTFNL omcr i959 UJ6u-334

1. A vehicular remote power supply adapted for use with a vehicleelectrical system including a d.c. voltage source; a generator havingarmature and field terminals for producing a d.c. output voltage; aregulator having a field terminal, a battery terminal connected to saidvoltage source, and an armature terminal connected to said generatorarmature terminal; said generator being driven by the internalcombustion engine of the vehicle controlled by throttle means; saidremote power supply comprising: a. means for connecting said generatorarmature terminal to a load having a relatively high d.c. voltagerequirement; b. electrically operated switching means normallyconnecting said generator field terminal to said regulator fieldterminal and operable when electrically energized to disconnect saidgenerator field terminal from said regulator field terminal and toconnect said generator field terminal to said d.c. voltage source; c.energizing means for selectively connecting said d.c. voltage source tosaid switching means for causing operation thereof; and d. protectiveswitching means operable to disconnect said generator armature terminalfrom said d.c. voltage source after said throttle means has beenadvanced through a predetermined distance.
 2. Apparatus according toclaim 1 further including electromechanical means mechanically connectedto said throttle means and electrically coupled by said electricallyoperated switching means to said d.c. voltage source for moving saidthrottle means to increase engine speed when said electro-mechanicalmeans is energized by said d.c. voltage source.
 3. Apparatus accordingto claim 2 wherein said protective switching means is mechanicallycoupled to said electromechanical means and normally connects saidgenerator armature terminal to said d.c. voltage source and operates todisconnect said generator armature terminal from said d.c. voltagesource when said electromechanical means has advanced said throttlemeans through a predetermined distance.
 4. Apparatus according to claim3 wherein said protective switching means also normally connects saidd.c. voltage source to said electromechanical means and disconnects saidd.c. source from said electromechanical means also when said throttlemeans has been moved through said predetermined distance, and whereinsaid electromechanical means includes holding circuit means connected tosaid d.c. voltage source by said electrically operated switching meanswhen the latter is operated.
 5. Apparatus according to claim 1 whereinsaid load-connecting means includes current responsive means and whereinsaid energizing means is connected in controlled relation to saidcurrent responsive means whereby said energizing means connects saidd.c. voltage source to said electrically operated switching means onlywhen a load is connected to said generator armature terminal. 6.Apparatus according to claim 1 wherein the load is a battery to becharged having opposite polarity terminals, wherein said energizingmeans includes manually operated switching means for connecting saidd.c. voltage source to said electrically operated switching means, andwherein said load connecting means includes isolation switch meansconnected in controlled relation to said energizing means for connectingsaid battery to be charged to said generator armature terminal when saidelectrically operate switching means is energized.
 7. Apparatusaccording to claim 6 further including alarm means connected to saidload connecting means for indicating an improper polarity connection ofsaid battery terminals relative to said generator armature terminal. 8.Apparatus according to claim 1 wherein the load comprises weldingelectrode means adapted to be brought into engagement with a workpiece,wherein said load-connecting means includes means responsive toengagement of said welding electrode means with said workpiece, whereinsaid energizing means is connected in controlled relation to saidengagement responsive meanS whereby said electrically operated switchingmeans is operated when said welding electrode means is in engagementwith said workpiece, and wherein said apparatus further comprisesswitching means connected in controlled relation to said energizingmeans and normally connecting said generator field terminal to saidregulator field terminal and operated by said energizing means todisconnect said generator field terminal from said regulator fieldterminal and to connect said generator field terminal to said generatorarmature terminal whereby said generator is electrically self-excited.9. Apparatus according to claim 8 wherein said energizing means includestime delay means for operating said electrically operated switchingmeans only a predetermined time after engagement between said weldingelectrode means and said workpiece.
 10. Apparatus according to claim 1wherein said electrically operated switching means comprises relay meanshaving a control coil connected between said energizing means andelectrical ground, a first switching means connecting said generatorfield terminal to either said regulator field terminal or said d.c.voltage source depending upon the electrical condition of said coil, anda second switching means electrically connecting said electromechanicalmeans to said d.c. voltage source when said coil is energized. 11.Apparatus according to claim 2 wherein said electro-mechanical meanscomprises solenoid means having a coil connected between said d.c.source and said electrically operated switching means in a manner so asto be energized when said switching means is operated and a plungermechanically connected to said throttle means for moving said throttlemeans in response to energization of said coil.
 12. Apparatus accordingto claim 10 wherein said energizing means includes normally open reedswitch means for connecting said d.c. source to said coil of saidelectrically operated switching means, said reed switch means having acontrol coil connected in series with said load-connecting means wherebysaid d.c. voltage source is connected to said coil of said electricallyoperated switching means only when a load is connected to said generatorarmature terminal.
 13. Apparatus according to claim 11 wherein saidelectromechanical means further includes a holding coil connected tosaid d.c. voltage source by said electrically operated switching meanswhen the latter is operated so as to maintain said plunger in a givenposition when said solenoid coil is de-energized, and wherein saidprotEctive switching means is operatively connected to said plunger andalso normally connects said d.c. voltage source to said solenoid coiland disconnects said coil when said plunger has moved said throttlemeans through said predetermined distance.
 14. Apparatus according toclaim 1 wherein the load comprises welding electrode means adapted to bebrought into engagement with a workpiece and wherein said energizingmeans comprises: a. first relay means including a coil and having afirst position wherein said electrically operated switching means isdisconnected from said d.c. voltage source and said generator fieldterminal is connected to said regulator field terminal and operable inresponse to a flow of current through said coil to a second positionconnecting said d.c. voltage source to said electrically operatedswitching means and connecting said generator field terminal to saidgenerator armature terminal whereby said generator is electricallyself-excited; b. means connecting one terminal of said coil to said d.c.voltage source; c. semiconductor switching means having a controlterminal and connected to the other terminal of said coil in a mannersuch that when said semiconductor means is rendered conducting currentflows through said relay coil; d. an R-C timing circuit connected tosaid semiconductor means control terminal whereby said semiconductormeans is switched into a conducting state a predetermined time delayafter a voltage of sufficient magnitude is applied to said timingcircuit; and e. a second relay means having a coil and operable toconnect a voltage of said sufficient magnitude to said timing circuit inresponse to energization of said coil, said coil being connected to saidload connecting means in a manner whereby said coil is energized inresponse to engagement of said welding electrode means with saidworkpiece.